package ErChaShuZuoYe.BinaryTree;

import java.util.LinkedList;
import java.util.Queue;

public class BinaryTree1 {
    static class TreeNode {
        public char val;
        public TreeNode left;//左孩子的引用
        public TreeNode right;//右孩子的引用

        public TreeNode(char val) {
            this.val = val;
        }
    }
    /**
     * 创建一棵二叉树 返回这棵树的根节点
     *
     * @return
     */
    public TreeNode createTree() {
        TreeNode A=new TreeNode('A');
        TreeNode B=new TreeNode('B');
        TreeNode C=new TreeNode('C');
        TreeNode D=new TreeNode('D');
        TreeNode E=new TreeNode('E');
        TreeNode F=new TreeNode('F');
        TreeNode G=new TreeNode('G');
        TreeNode H=new TreeNode('G');

        A.left=B;
        A.right=C;
        B.left=D;
        B.right=E;
        C.left=F;
        C.right=G;

        return A;
    }

    // 前序遍历
    public void preOrder(TreeNode root) {
        if(root==null){
            return;
        }
        System.out.println(root.val+" ");
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    void inOrder(TreeNode root) {
        if (root==null){
            return;
        }
        inOrder(root.left);
        System.out.println(root.val+" ");
        inOrder(root.right);
    }

    // 后序遍历
    void postOrder(TreeNode root) {
        if(root==null){
            return;
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.println(root.val+" ");
    }

    public static int nodeSize;

    /**
     * 获取树中节点的个数：遍历思路
     */
    void size(TreeNode root) {
        if (root==null){
            return;
        }
        nodeSize++;
        size(root.left);
        size(root.right);
    }

    /**
     * 获取节点的个数：子问题的思路
     *
     * @param root
     * @return
     */
    int size2(TreeNode root) {
        if (root==null){
            return 0;
        }
        return size2(root.left)+size2(root.right)+1;
    }
    /*
     获取叶子节点的个数：遍历思路
     */
    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
        if (root==null){
            return;
        }
        if(root.left==null&&root.right==null){
            leafSize++;
        }
        getLeafNodeCount1(root.left);
        getLeafNodeCount2(root.right);
    }

    /*
     获取叶子节点的个数：子问题
     */
    int getLeafNodeCount2(TreeNode root) {
        if (root==null){
            return 0;
        }
        if(root.left==null&&root.right==null){
            return 1;
        }
        return getLeafNodeCount2(root.left)
                +getLeafNodeCount2(root.right);
    }

    /*
    获取第K层节点的个数
     */
    int getKLevelNodeCount(TreeNode root, int k) {
        if (root==null){
            return 0;
        }
        if (k==1){
            return 1;
        }
        return getKLevelNodeCount(root.left,k-1)
                +getKLevelNodeCount(root.right,k-1);
    }
    /*
     获取二叉树的高度
     时间复杂度：O(N)
     */
    int getHeight(TreeNode root) {
        if (root==null){
            return 0;
        }
        int left1=getHeight(root.left);
        int right2=getHeight(root.right);

        //return Math.max(left1,right2)+1;
        return left1>right2?left1+1:right2+1;
    }

    // 检测值为value的元素是否存在
    TreeNode find(TreeNode root, char val) {
        if (root==null){
            return null;
        }
        if(root.val==val){
            return root;
        }
        TreeNode left21=find(root.left,val);
        if(left21!=null){
            return left21;
        }
        TreeNode left22=find(root.right,val);
        if(left22!=null){
            return left22;
        }
        return null;
    }
    //层序遍历
    void levelOrder(TreeNode root) {
        if(root==null){
            return;
        }
        Queue<TreeNode> queue=new LinkedList<>();
        queue.offer(root);
        while(queue!=null){
            TreeNode node=queue.poll();
            System.out.println(node.val+" ");
            if(node.left!=null){
                queue.offer(node.left);
            }
            if(node.right!=null){
                queue.offer(node.right);
            }
        }
        System.out.println();
    }
    // 判断一棵树是不是完全二叉树
    boolean isCompleteTree(TreeNode root) {
        if (root==null){
            return true;
        }
        Queue<TreeNode> queue=new LinkedList<>();
        queue.offer(root);

        while(!queue.isEmpty()){
            TreeNode cur =queue.poll();
            if(cur!=null){
                queue.offer(cur.left);
                queue.offer(cur.right);
            }else {
                break;
            }
        }
        while (!queue.isEmpty()) {
            TreeNode peek = queue.peek();
            if(peek != null) {
                return false;
            }
            queue.poll();
        }
        return true;

    }




    //2024714
    //反转二叉树
    public TreeNode invertTree(TreeNode root) {
        if(root==null){
            return null;
        }
        TreeNode tmp=root.left;
        root.left=root.right;
        root.right=tmp;
        invertTree(root.left);
        invertTree(root.right);
        return root;
    }

    //查看是否是相同二叉树
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if((p==null&&q!=null)||(p!=null&&q==null)){
            return false;
        }

        if(p==null&&q==null){
            return true;
        }

        if(p.val!=q.val){
            return false;
        }
        return isSameTree(p.left,q.left)&&isSameTree(p.right,q.right);
    }
}
